__________________________ Posted February 2, 2015 Posted February 2, 2015 How do I determine the torque bias on a Torsen diff (how much more torque the greater-traction wheel gets than the lower-traction wheel)? Thanks. I'm most curious about this one (and how much torque and rotational speed it could handle): http://www.brickshelf.com/cgi-bin/gallery.cgi?f=259949 Quote
Hrafn Posted February 3, 2015 Posted February 3, 2015 How do I determine the torque bias on a Torsen diff (how much more torque the greater-traction wheel gets than the lower-traction wheel)? Thanks. I'm most curious about this one (and how much torque and rotational speed it could handle): http://www.brickshel...ry.cgi?f=259949 As far as I can tell, neither that nor any of the other "Torsen" diffs made of Lego are actually proper Torsen diffs. They don't sense torque; instead the diff locks when the the angular position of the two shafts differs by enough. They only unlock if that angular difference is reduced. In other words, there is no torque bias because this is a locking, not a limited-slip, differential; and the locking is based on relative angular position, not angular speed or torque. True mechanical torque-sensing differentials seem to require helical gears, which Lego does not make. There are simple ways of making limited-slip differentials with rubber bands connecting the half-shafts to a common third shaft, and those work reasonably well at low torque. Quote
Tommy Styrvoky Posted February 3, 2015 Posted February 3, 2015 It seems with this diff that it is prone to separating, and the axles are weakly supported. Quote
Saberwing40k Posted February 3, 2015 Posted February 3, 2015 (edited) I'm fairly certain that in order to have any kind of torque bias, there needs to be a difference in the gearing of the axles on either side of a differential. Also, this differential is not strong at all, and will break apart as soon as it locks up. I speak from personal knowledge, as I have build this particular design, and have tested it. If you want a limited slip differential, Thirdwigg has build some in his trial trucks. Kenworth T55 Driveline by thirdwigg, on Flickr However, from my experience, differentials in most kinds of Lego trial trucks are rather counterproductive, even if they are limited slip. Edited February 3, 2015 by Saberwing40k Quote
Epic Technic Posted February 3, 2015 Posted February 3, 2015 You're better off just buying effermen's torsen diff off shapeways. Sariel tested it and he said it worked Quote
__________________________ Posted February 3, 2015 Author Posted February 3, 2015 You're better off just buying effermen's torsen diff off shapeways. Sariel tested it and he said it worked Thanks! I read that article http://sariel.pl/2014/10/dune-buggy/ and , but I didn't know it used a Torsen diff. I will buy one of these. The small size is super impressive! How much torque or rpm can it handle, though? Quote
Sariel Posted February 3, 2015 Posted February 3, 2015 The small size is super impressive! How much torque or rpm can it handle, though? It's not that very small. I was unable to damage it with torque so far. Keep in mind that this is a complex 3D printed part, it may require some filing before it works properly. Quote
Thirdwigg Posted February 3, 2015 Posted February 3, 2015 My idea worked well, but in most situations, you loose traction at the tires before the limited slip starts to act. Quote
__________________________ Posted February 3, 2015 Author Posted February 3, 2015 (edited) It's not that very small. I was unable to damage it with torque so far. Keep in mind that this is a complex 3D printed part, it may require some filing before it works properly. If I have 5 L motors hard-coupled, geared from between 1:1 and 1:9, would Efferman's Torsen Diff be damaged? Also, would you recommend it in a "supercar", compared to a lockable diff? Edited February 3, 2015 by TheLegoExpert Quote
Sariel Posted February 3, 2015 Posted February 3, 2015 If I have 5 L motors hard-coupled, geared from between 1:1 and 1:9, would Efferman's Torsen Diff be damaged? Also, would you recommend it in a "supercar", compared to a lockable diff? Your guess is as good as mine. And I'm not sure you need a Torsen or a lockable driff in a supercar, I mean supercars don't really go off-road. Quote
__________________________ Posted February 3, 2015 Author Posted February 3, 2015 Your guess is as good as mine. And I'm not sure you need a Torsen or a lockable driff in a supercar, I mean supercars don't really go off-road. If it did go off-road the Torsen diff would be useless; it'll be for in case one wheel gets in water/ice/slippery grass/etc. Quote
Sariel Posted February 3, 2015 Posted February 3, 2015 water/ice/slippery grass/etc. Exactly the list of things I've never seen Lego supercars driving on :) Quote
__________________________ Posted February 3, 2015 Author Posted February 3, 2015 Exactly the list of things I've never seen Lego supercars driving on :) Audi has used it since 1986 http://www.audi-technology-portal.de/en/drivetrain/quattro_en/torsen-differential :) Quote
Saberwing40k Posted February 4, 2015 Posted February 4, 2015 Audi has used it since 1986 http://www.audi-tech...en-differential :) Yeah, but what works for Lego cars and what works for real cars are very different things. Most Lego cars do not need any kind of advanced suspension geometry, or brakes, for that matter. Also, like Sariel said, I have never seen a Lego supercar encounter a slip or odd traction situation that would require a limited slip differential. Quote
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